Well, we have seen how authoritarian repression of alternative viewpoints turned out, with the imprisonment of Galileo, execution of Thomas More, horrors of Stalin and Hitler and too many more to mention.
And we have seen what immense improvements of the conditions of man came through a free society like the founding of USA, with freedom of speech and eventual total abolishment of slavery. (Slavery, which up to then more-or-less had been part of the vast majority of civilizations, from Asia to Africa, to America, to Europe).
And now you argue to run that experiment again, just to be sure?
The United States abolished slavery later than most other Western countries,
including the British Empire,
and at its founding was "free" only for a minority of white, land-owning males.
While the Bill of Rights protected local elites from dictates of the federal government,
it was not applied to state governments until the 20th century.
State-level blasphemy laws were applied up until the 1930s:
https://en.wikipedia.org/wiki/Blasphemy_law_in_the_United_St....
Additionally, free speech was applied highly unevenly throughout the 20th century.
The 1960-70s liberation movements that gave us most of our substantive freedoms
were fought viciously by the US government,
with methods that went as far as assassination:
https://en.wikipedia.org/wiki/COINTELPRO.
This, however, is not particularly relevant to content moderation on websites.
The US wasn't like this in terms of free speech right off the bat (in both legal and cultural terms), and your historical analogies aren't well-supported. Stalin was able to kill a lot of people due to, inter alia, a lack of what we could term "the rule-of-law", and he did it in part to direct as many resources as possible towards industrialization. Hitler is a demagogue who arguably took advantage of a situation where anyone could say almost anything, and where faith in more standard institutions was low.
Nobody is advocating for actually punishing people based on what they say, let alone in as dire a manner as execution, so the examples of Galileo and Moore are irrelevant.
And we have seen what immense improvements of the conditions of man came through a free society like the founding of USA, with freedom of speech and eventual total abolishment of slavery. (Slavery, which up to then more-or-less had been part of the vast majority of civilizations, from Asia to Africa, to America, to Europe).
And now you argue to run that experiment again, just to be sure?